Spinal implants such as spinal interbody fusion devices are used to treat degenerative disc disease and other damages or defects in the spinal disc between adjacent vertebrae. The disc may be herniated or suffering from a variety of degenerative conditions, such that the anatomical function of the spinal disc is disrupted. Most prevalent surgical treatment for these conditions is to fuse the two vertebrae surrounding the affected disc. In most cases, the entire disc will be removed, except for a portion of the annulus, by way of a discectomy procedure. A spinal fusion device is then introduced into the intradiscal space and suitable bone graft or bone substitute material is placed substantially in and/or adjacent the device in order to promote fusion between two adjacent vertebrae.
There are various approaches that a surgeon may take to perform spinal fusion. Such approaches include a posterior approach, which is accessed from the back of the spine, or an anterior approach, which is accessed from the front. Other approaches which may be used include a posterolateral approach, an anterior lateral approach, and a lateral approach which is accessed from the side of the patient. The particular approach selected is primarily determined by the type of treatment to be administered by the surgeon. For patients that require treatment for conditions including degenerative disc disease, spinal instability or deformity, anterior lumbar interbody fusion (ALIF) has been found to be effective. The ALIF procedure and associated devices have certain advantages over other procedures. The first is that there is typically less disruption to surrounding musculature and nerves. Once access is achieved, there is a relatively open space to work in. This allows for more efficient removal of disc material thereby providing a larger potential fusion bed. The ALIF procedure also allows for a larger implant both in footprint and height, which creates better height and lordosis restoration as well as greater spinal stability.
Anterior lumbar interbody fusion requires an incision through the patient's abdomen and retraction of the surrounding muscles and abdominal contents to the side. After the affected disc is removed a structural ALIF device or implant is inserted which may be packed before, during or after insertion with a suitable bone graft material. Having a modular implant system has been found to be advantageous for an ALIF procedure as well as other procedures. This is desirable because it provides the surgeon the means to optimize fit and function of the implant system based on surgical preference. Specifically, having various implant configurations allows for complete functional modularity during a given procedure including: full construct (standalone indication with integrated fixation), cage-plate (supplemental fixation indication), and cage alone (supplemental fixation indication) configurations. Furthermore, it allows for maximizing visualization within the disc space, optimizing grafting volume/potential through post-pack, and promoting greater fusion by allowing for more efficient endplate preparation. Finally, it provides a baseline system from which other useful implant configurations and/or components can be added.
Known modular spinal implant systems are disclosed, for example, in U.S. Patent Publication 2014/0277456, entitled “Spinal Implant and Assembly”, published Sep. 18, 2014 and filed by David Louis Kirschman, and in U.S. Patent Publication 2012/0197401, entitled “Interbody Spinal Implants with Modular Add-on Devices”, published Aug. 2, 2012 and filed by James Duncan et al. While filling certain surgical needs, there is still interest in improved modular interbody devices fusion devices.